1 files changed, 120 insertions, 0 deletions
diff --git a/download.py b/download.py
new file mode 100755
index 0000000..fdaa3f4
--- /dev/null
+++ b/download.py
@@ -0,0 +1,120 @@
+#!/usr/bin/env python3
+
+import requests
+import datetime
+import pytz
+import requests
+import os
+
+from multiprocessing import cpu_count
+from multiprocessing.pool import ThreadPool
+
+import subprocess
+
+import misc
+
+BASE='https://opendata.dwd.de/weather/nwp'
+
+def get_current_run():
+    # we allow up to 3h of slack for DWD to upload the latest run
+    tz = pytz.timezone('UTC')
+    now = datetime.datetime.now(datetime.timezone.utc)
+    corrected = now - datetime.timedelta(hours=3)
+
+    run = int(corrected.hour / 6) * 6
+
+    return (f'{run:02d}', corrected.strftime('%Y%m%d'))
+
+def download_url(args):
+    url, dest = args
+    r = requests.get(url)
+    try:
+        with open(dest, 'wb') as f:
+            f.write(r.content)
+        print(f'Downloaded {dest}')
+    except Exception as e:
+        print(f'Failed to download {dest}:\n', e)
+
+def unpack_bz2(dest):
+    res = subprocess.run(['bzip2', '-df', dest])
+    if res.returncode != 0:
+        print(f'There was an error unpacking {dest}:', res.stderr)
+
+def download_dwd_gribs(config, date, run, target):
+    model = config['model']
+    model_long = config['model_long']
+
+    misc.create_output_dir(config['output'])
+
+    to_download = []
+
+    for step in config['steps']:
+        step_str = f'{step:03d}'
+
+        for parameter in config['pressure_level_parameters']:
+            parameter2 = parameter.upper() if config['parameter_caps_in_filename'] else parameter
+
+            for level in config['pressure_levels']:
+                filename = f'{model_long}_regular-lat-lon_pressure-level_{date}{run}_{step_str}_{level}_{parameter2}.grib2.bz2'
+                URL = f'{BASE}/{model}/grib/{run}/{parameter}/{filename}'
+
+                to_download.append((URL, os.path.join(config['output'], filename)))
+
+        for parameter in config['single_level_parameters']:
+            parameter2 = parameter.upper() if config['parameter_caps_in_filename'] else parameter
+            filename = f'{model_long}_regular-lat-lon_single-level_{date}{run}_{step_str}_{parameter2}.grib2.bz2'
+            URL = f'{BASE}/{model}/grib/{run}/{parameter}/{filename}'
+
+            to_download.append((URL, os.path.join(config['output'], filename)))
+
+
+    for _ in ThreadPool(cpu_count()).imap_unordered(download_url, to_download):
+        pass
+
+    print('Done Downloading. Uncompressing...')
+
+    for _ in ThreadPool(cpu_count()).imap_unordered(unpack_bz2, [dest for _, dest in to_download]):
+        pass
+
+    downloaded_gribs = [dest.removesuffix('.bz2') for _, dest in to_download]
+
+    res = subprocess.run(['grib_copy'] + downloaded_gribs + [target])
+    if res.returncode != 0:
+        print('grib_copy failed with: ', res.stderr)
+
+    res = subprocess.run(['rm', '-f'] + downloaded_gribs)
+    if res.returncode != 0:
+        print('rm failed with: ', res.stderr)
+
+def load_data(config):
+    run, date = get_current_run()
+    target = os.path.join(config['output'], f'combined_{date}_{run}.grib2')
+
+    if not os.path.exists(target):
+        download_dwd_gribs(config, date, run, target)
+
+config = {
+    'output':'dwd_icon-eu',
+    'model':'icon-eu',
+    'model_long':'icon-eu_europe',
+    'parameter_caps_in_filename':True,
+    'pressure_level_parameters': [
+        't',
+        'relhum',
+        'u',
+        'v',
+        'fi',
+        'clc'
+    ],
+    'single_level_parameters': [
+        'pmsl',
+        't_2m',
+        'relhum_2m'
+    ],
+    'pressure_levels':[ 1000, 950, 925, 900, 875, 850, 825, 800, 775, 700, 600, 500, 400, 300, 250, 200, 150, 100 ],
+    'steps':[0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48]
+}
+
+if __name__ == '__main__':
+    load_data(config)
+